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<blockquote data-quote="John Roberts" data-source="post: 27399" data-attributes="member: 126">Re: Thoughts about amplifiers at 3/4 volume.Thanks for clearing that up... I was thinking it was answered too many times. This ASSumes the church in the OP&#039;s question was set up by a &quot;competent&quot; anything...While correct wrt peak voltage and peak power, as we should have observed by now typical system operators often drive amplifiers past clipping to increase the average voltage and average output power further. Hopefully not so much in churches, but it is no accident that amps have the capability to be used that way, and clip limiters have tens of dB of gain reduction range. So yes you can maximize (peak) dynamic range by lining up clipping to be the same, but many amps have the capability to be operated beyond clipping with clip limiters. So this becomes a trade off between lowest possible noise floor, and pulling max power from the amps.&nbsp; In an ideal world people (and i guess &quot;competent installer/system engineers&quot;) don&#039;t clip amps. In the real world they do.&nbsp; In church applications as in the OP&#039;s question, this is IMO the exact tradeoff being considered, louder output or less residual noise. They went for less noise.&nbsp; &quot;Thin&quot; sounds like it is describing something other than a simple gain trim. I can&#039;t guess what, so I won&#039;t.While correct about noise floor contribution from later gain stages, this is confusing in the context of the power amp trim, since you are in fact operating closer to it&#039;s noise floor by trimming back the input gain while simultaneously improving the system S/N. While you may be adding some tiny fraction of a dB of the amplifiers noise, the several dB of reduction to the much louder system noise will swamp this out. So this is a true but completely irrelevant factoid.&nbsp; System noise floor will typically be dominated by the microphone and preamp, unless the preamp trim is mis-adjusted.This is actually a possibility but I would expect pretty rare. One more than I&#039;ve ever seen... but who knows?&nbsp;&nbsp; Most do have an active stage before the passive pad so can still be overloaded in theory, but not in practice for decent designs. Yup, Chuck&#039;s old article is a classic. JR</blockquote>

[QUOTE="John Roberts, post: 27399, member: 126"] Re: Thoughts about amplifiers at 3/4 volume. Thanks for clearing that up... I was thinking it was answered too many times. This ASSumes the church in the OP's question was set up by a "competent" anything... While correct wrt peak voltage and peak power, as we should have observed by now typical system operators often drive amplifiers past clipping to increase the average voltage and average output power further. Hopefully not so much in churches, but it is no accident that amps have the capability to be used that way, and clip limiters have tens of dB of gain reduction range. So yes you can maximize (peak) dynamic range by lining up clipping to be the same, but many amps have the capability to be operated beyond clipping with clip limiters. So this becomes a trade off between lowest possible noise floor, and pulling max power from the amps. In an ideal world people (and i guess "competent installer/system engineers") don't clip amps. In the real world they do. In church applications as in the OP's question, this is IMO the exact tradeoff being considered, louder output or less residual noise. They went for less noise. "Thin" sounds like it is describing something other than a simple gain trim. I can't guess what, so I won't. While correct about noise floor contribution from later gain stages, this is confusing in the context of the power amp trim, since you are in fact operating closer to it's noise floor by trimming back the input gain while simultaneously improving the system S/N. While you may be adding some tiny fraction of a dB of the amplifiers noise, the several dB of reduction to the much louder system noise will swamp this out. So this is a true but completely irrelevant factoid. System noise floor will typically be dominated by the microphone and preamp, unless the preamp trim is mis-adjusted. This is actually a possibility but I would expect pretty rare. One more than I've ever seen... but who knows? Most do have an active stage before the passive pad so can still be overloaded in theory, but not in practice for decent designs. Yup, Chuck's old article is a classic. JR [/QUOTE]

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